As technology continues to reduce the size of electronic devices and make them more capable of performing multiple tasks, various forms of information transmission are finding their way into an increasing number of products and applications as disclosed in J. Boone, et al., “Wireless Technology Will Improve Life Quality,” on a GroupT my statement blog, 2011; M. Kolberg, M. Merabti, S. Moyer, “Trends in Consumer Communications: More Services and Media, Less Wires,” in IEEE Communications Magazine: June 2010; and A. Goldsmith, “Wireless Communications,” Cambridge University Press., 2005.
In conjunction with this increase, the amount of available unlicensed wireless spectrum continues to shrink and the unlicensed bands are becoming more as disclosed in J. D, Watson, et al., “Simulation and Analysis of Extended Brake Lights for Inter-Vehicle Communication Networks,” in Distributed Computing Systems Workshops 2007, 2007, Given the plethora of different standards and applications for these wireless technologies, electromagnetic (EM) interference from other users or protocols poses a serious risk. Furthermore, with an increasing number of wireless communication applications being implemented, the security of the transmitted data is rapidly becoming a serious concern for those trying to protect personal or sensitive information as seen in S. Bar-On, “Hi-Tech Heist,” on CBS News and online at cbsnews.com, 2009 and A. Greenberg, “Hacker's Demo Shows How Easily Credit Cards Can Be Read Through Clothes And Wallets,” 2012.
To address some of these problems, a new field of information transmission via visual communications has been emerging, where information is transmitted using the visual light spectrum. By using the visual light spectrum, spectrum licensing is no longer an issue. Additionally, interference from other users is drastically reduced over similar systems, due to the LOS visual channel that is used in such a system. This is a desirable feature for any form of information transmission for applications such as commercial transactions, surveillance/national defense and medical/health networks.
Research into visual communication offers the potential to solve some of the aforementioned issues, as shown in T. D. C. Little et al., “Using LED Lighting for Ubiquitous Indoor Wireless Networking,” in IEEE International Conference on Wireless and Mobile. Computing, Networking and Communication, 2008; M. Wada et al., “Road-to-Vehicle Communication Using LED Traffic Light,” in IEEE Intelligent Vehicles Symposium, 2005; and J. D. Watson, et al., “Simulation and Analysis of Extended Brake Lights for Inter-Vehicle Communication Networks,” in Distributed Computing Systems Workshops 2007.
Direct visual communications through the use of imaging systems are also becoming more popular. Limited throughput information transmission systems have emerged from the widely deployed camera imaging systems built within mobile devices. Furthermore, limited amounts of data can now be transferred by (Quick Response) QR codes and 2D barcodes as disclosed in ISO. See Automatic identification and data capture techniques, QR code 2005 bar code symbology specification, ISO/IEC 18004:2006, 2006 and Automatic identification and data capture techniques, Data Matrix bar code symbology specification, ISO/IEC 16022:2006.
Expanding visual communications to leverage video imaging systems is something that is beginning to be explored as disclosed in S. Hranilovic, Kschischang, “A Pixelated MIMO Wireless Optical Communication System,” in IEEE Journal of Selected Topics in Quantum Electronics, Vol. 12, No. 4, 2006; A. Ashok, et al., “Characterizing Multiplexing and Diversity in Visual MIMO,” in 45th Annual Conference on Information Sciences and Systems (CISS): 2011, 2011; and S. D. Perli, “Pixnet: Designing interference-free Wireless Links using LCD-Camera Pairs,” submitted to Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 2010.
Video communication systems sequentially process stacks of images in order to make up frames of a video that can transmit far more data. For instance, the pixilated MIMO method employs a digital camera to receive a video stack of pixilated images from a computer screen with a focus primarily on the channel used in such communications. Similar work, a concept called “Visual MIMO”, expanded the general approach presented in by noting that, most of the distortion in such a system would not come from the channel, but instead from the perspective distortions in the receiver. Further work in the development of a system called Pixnet looked into a similar approach of using LCD screens as a transmitter and cameras as receivers with the focus on trying to maximize throughput, while mitigating distortions and losses due to multi-meter distances and off center viewing angles.
These research activities demonstrate the capabilities of visual information transmission systems and present potential uses for them, but are limited to the hardware that can be used in such a system. With video cameras built into most mobile electronic devices, the viability of turning any of these devices into a visual communications receiver with only a software package has yet to be investigated. Furthermore, these devices as well as many other devices have a digital screen to display graphics, making many devices candidates for transmitters. Much of the analysis into the transmission distance and reception area explored in previous research efforts can also be mitigated by requiring closer range communication between devices, similar to the requirements of QR codes.
A need, therefore, exists for an improved method and system for visible LOS communications.